Interferon-gamma gene dinucleotide (CA) repeat and interleukin-4 promoter region (-590C/T) polymorphisms in Japanese patients with endometriosis.

BACKGROUND Endometriosis is a multifactorial disease with possible genetic predisposition and involvement of environmental factors in its pathogenesis. Cytokines may play important roles in the pathogenesis of endometriosis. The aim of this study was to investigate whether the interferon-gamma gene (IFNG) CA-repeat and interleukin-4 (IL-4) promoter region (-590C/T) polymorphisms may be responsible in part for genetic susceptibility to endometriosis. METHODS IFNG CA-repeat and IL-4 -590C/T polymorphisms were determined for 185 patients with endometriosis and 176 healthy fertile women by quantitative genescan technology and PCR-restriction fragment length polymorphism analysis, respectively. Patients with endometriosis were analysed further according to their stage of disease, the presence or absence of chocolate cysts and whether or not their disease was associated with adenomyosis and/or lyomyomata. RESULTS The global IFNG allele frequencies in the patients with endometriosis were significantly different from those in the control women (chi2 = 12.964, 6 df, P = 0.0436). The difference was due to an increase of the a13 (114 bp) allele in patients with endometriosis (chi2 = 10.222, P = 0.0088, corrected P = 0.0352, odds ratio = 1.48, 95% confidence interval = 1.10-1.98). There were no differences in IL-4 -590C/T genotypes and allele frequencies between control women and all patients with endometriosis or between control women and each subgroup of patients with endometriosis. CONCLUSION The results suggest that the IFNG CA-repeat polymorphism is associated with susceptibility to endometriosis in a Japanese population.